Efficient and robust acknowledgement procedure for new radio operation in unlicensed band

Abstract

To provide systems for efficient and robust handling of acknowledgements in new radio unlicensed bands (NR-U) environments.SOLUTION: A wireless transmit receive unit (WTRU) may receive control information and a data transmission from a gNB in a first channel occupancy time. The control information may include an indication of uplink resources. The data transmission may require some sort of acknowledgement. The WTRU may attempt to transmit the acknowledgement in the indicated uplink resources, but the gNB may not receive the acknowledgement. When the WTRU receives control information and a data transmission in a second channel occupancy time, including an indication to aggregate any previously unsuccessful acknowledgement transmissions, the WTRU may transmit an aggregated acknowledgement including previous unsuccessful acknowledgements and any additional acknowledgements. In some cases, look-before-talk procedures may be used.SELECTED DRAWING: Figure 8

Description

[Background technology]

[0001] Priority claims This patent application claims the benefit of U.S. Provisional Patent Application No. 62 / 716,211, filed August 8, 2018, and U.S. Provisional Patent Application No. 62 / 753,457, filed October 31, 2018, the contents of which are incorporated herein by reference.

[0002] In the field of wireless communications, next generation air interfaces such as New Radio can support a wide range of use cases with different spectrum usage models, such as licensed, unlicensed / shared, etc. To operate in shared spectrum, systems, methods, and apparatus may be required to enable efficient and robust wireless communications in unlicensed bands. Summary of the Invention

[0003] A system, method, and apparatus for efficiently and robustly handling acknowledgments in a new unlicensed radio spectrum (NR-U) environment. A wireless transmit / receive unit (WTRU) can receive control information and data transmissions from a gNB in ​​a first interval (i.e., a transport block or channel occupation time), where the control information can include an indication of uplink resources. The data transmission may require some type of acknowledgment (i.e., HARQ feedback). The WTRU can attempt to transmit an acknowledgment on the indicated uplink resources, but the gNB may not receive the acknowledgment. The WTRU can receive control information and data transmissions from the gNB in ​​a second interval that includes an indication to aggregate previously failed acknowledgment transmissions. The WTRU can transmit an aggregated acknowledgment that includes the previous failed acknowledgments and any additional acknowledgments from the current interval. In some cases, a look-before-talk procedure can be used.

[0004] A more detailed understanding may be had from the following description, given by way of example in conjunction with the accompanying drawings, in which like reference numerals indicate similar elements and in which: [Brief explanation of the drawings]

[0005] [Figure 1A] FIG. 1A is a system diagram illustrating an example communication system in which one or more disclosed embodiments may be implemented. [Figure 1B] FIG. 1B is a system diagram illustrating an example wireless transmit / receive unit (WTRU) that can be used within the communication system shown in FIG. 1A, according to an embodiment. [Figure 1C] FIG. 1C is a system diagram illustrating an example radio access network (RAN) and an example core network (CN) that can be used within the communication system shown in FIG. 1A, according to an embodiment. [Figure 1D] FIG. 1D is a system diagram illustrating a further exemplary RAN and a further exemplary CN that can be used within the communication system shown in FIG. 1A, according to an embodiment. [Figure 2] FIG. 2 is an example transmission diagram in which a WTRU fails an LBT procedure. [Figure 3] FIG. 3 is an example transmission diagram in which a WTRU fails an LBT procedure. [Figure 4] FIG. 4 is an example transmission diagram in which a WTRU may have non-exclusive PUCCH priorities. [Figure 5] FIG. 5 is an example transmission diagram in which the WTRU successfully completes the LBT, but the gNB fails to detect the PUCCH. [Figure 6] FIG. 6 is an example transmission diagram in which the WTRU prepares a HARQ codebook according to at least the DAI and / or the EDAI. [Figure 7] FIG. 7 is an example transmission diagram in which the WTRU prepares a HARQ codebook according to at least the DAI and / or the EDAI. [Figure 8]FIG. 8 is an example transmission diagram in which a WTRU aggregates HARQ codebooks based on the EDAI of one or more COTs. [Figure 9] FIG. 9 is an example transmission diagram in which the PUCCH resource allocation is outside the COT and a PUCCH from a later COT is used. [Figure 10] FIG. 10 is an example transmission diagram in which a WTRU examines attributes of a scheduled PUCCH to determine gap-free transmission. [Figure 11] FIG. 11 is an exemplary procedure for conflict window adjustment. [Figure 12] FIG. 12 is an example transmission diagram of basic COT sharing. [Figure 13] FIG. 13 is an example transmission diagram of COT sharing that limits the effect of hidden nodes. DETAILED DESCRIPTION OF THE INVENTION

[0006] 1A illustrates an exemplary communication system 100 in which one or more disclosed embodiments can be implemented. The communication system 100 may be a multi-access system that provides content, such as voice, data, video, messaging, broadcasts, and the like, to multiple wireless users. The communication system 100 may enable the multiple wireless users to access such content through the sharing of system resources, including wireless bandwidth. For example, the communication system 100 may employ one or more channel access schemes, such as code division multiple access (CDMA), time division multiple access (TDMA), frequency division multiple access (FDMA), orthogonal FDMA (OFDMA), single-carrier FDMA (SC-FDMA), zero-tailed unique word DFT-spread OFDM (ZT UW DTS-s OFDM), unique word OFDM (UW-OFDM), resource block filtering OFDM, filter bank multicarrier (FBMC), and the like.

[0007] 1A, communications system 100 may include wireless transmit receive units (WTRUs) 102a, 102b, 102c, 102d, RANs 104 / 113, CNs 106 / 115, public switched telephone network (PSTN) 108, the Internet 110, and other networks 112, although it will be understood that the disclosed embodiments contemplate any number of WTRUs, base stations, networks, and / or network elements. Each of WTRUs 102a, 102b, 102c, 102d may be any type of device configured to operate and / or communicate in a wireless environment. By way of example, the WTRUs 102a, 102b, 102c, 102d (any of which may be referred to as a “station” and / or “STA”) may be configured to transmit and / or receive wireless signals and may include user equipment (UE), mobile stations, fixed or mobile subscriber units, subscription-based units, pagers, mobile phones, personal digital assistants (PDAs), smartphones, laptops, netbooks, personal computers, wireless sensors, hotspots or Mi-Fi devices, Internet of Things (IoT) devices, watches or other wearables, head-mounted displays (HMDs), vehicles, drones, medical devices and applications (e.g., remote surgery), industrial devices and applications (e.g., robots and / or other wireless devices operating in the context of industrial and / or automated processing chains), consumer electronics devices, device networks operating over commercial and / or industrial wireless, etc. Any of the WTRUs 102a, 102b, 102c, and 102d may be referred to interchangeably as a WTRU / UE.

[0008] The communications system 100 may also include a base station 114a and / or a base station 114b. Each of the base stations 114a, 114b may be any type of device configured to wirelessly interface with at least one of the WTRUs 102a, 102b, 102c, 102d to facilitate access to one or more communications networks, such as the CN 106 / 115, the Internet 110, and / or other networks 112. By way of example, the base stations 114a, 114b may be a base transceiver station (BTS), a Node-B, an eNode-B, a Home Node-B, a Home eNode-B, a gNB, an NR Node-B, a site controller, an access point (AP), a wireless router, etc. While the base stations 114a, 114b are each shown as a single element, it will be understood that the base stations 114a, 114b may include any number of interconnected base stations and / or network elements.

[0009] The base station 114a may be part of the RAN 104 / 113, which may also include other base stations and / or network elements (not shown), such as a base station controller (BSC), a radio network controller (RNC), relay nodes, etc. The base station 114a and / or base station 114b may be configured to transmit and / or receive wireless signals on one or more carrier frequencies, which may be referred to as a cell (not shown). These frequencies may be licensed spectrum, unlicensed spectrum, or a combination of licensed and unlicensed spectrum. A cell may provide wireless service coverage for a particular geographic area, which may be relatively fixed or may change over time. A cell may be further divided into cell sectors. For example, the cell associated with the base station 114a may be divided into three sectors. Thus, in one embodiment, the base station 114a may include three transceivers, i.e., one for each sector of the cell. In an embodiment, the base station 114a may employ multiple-input multiple-output (MIMO) technology and utilize multiple transceivers for each sector of the cell. For example, beamforming can be used to transmit and / or receive signals in desired spatial directions.

[0010] The base stations 114a, 114b may communicate with one or more WTRUs 102a, 102b, 102c, 102d over an air interface 116, which may be any suitable wireless communication link (e.g., radio frequency (RF), microwave, centimeter wave, microwave, infrared (IR), ultraviolet (UV), visible light, etc.). The air interface 116 may be established using any suitable radio access technology (RAT).

[0011] More specifically, as noted above, the communication system 100 may be a multiple-access system and may employ one or more channel access schemes, such as CDMA, TDMA, FDMA, OFDMA, SC-FDMA, etc. For example, the base stations 114a and WTRUs 102a, 102b, 102c of the RANs 104 / 113 may implement a radio technology such as Universal Mobile Telecommunications System (UMTS) Terrestrial Radio Access (UTRA), which may establish the air interfaces 115 / 116 / 117 using Wideband CDMA (WCDMA). WCDMA may include communication protocols such as High Speed ​​Packet Access (HSPA) and / or Evolved HSPA (HSPA+). HSPA may include High Speed ​​Downlink (DL) Packet Access (HSDPA) and / or High Speed ​​UL Packet Access (HSUPA).

[0012] In an embodiment, the base station 114a and the WTRUs 102a, 102b, 102c may implement a radio technology such as Evolved UMTS Terrestrial Radio Access (E-UTRA), which may establish the air interface 116 using Long Term Evolution (LTE) and / or LTE-Advanced (LTE-A) and / or LTE-Advanced Pro (LTE-A Pro).

[0013] In an embodiment, the base station 114a and the WTRUs 102a, 102b, 102c may implement a radio technology such as New Radio (NR) access, which may establish the air interface 116 using NR.

[0014] In an embodiment, the base station 114a and the WTRUs 102a, 102b, 102c may implement multiple radio access technologies. For example, the base station 114a and the WTRUs 102a, 102b, 102c may jointly implement LTE radio access and NR radio access, e.g., using a dual connectivity (DC) principle. Thus, the air interface utilized by the WTRUs 102a, 102b, 102c may be characterized by multiple types of radio access technologies and / or transmissions sent to and from multiple types of base stations (e.g., eNBs and gNBs).

[0015] In other embodiments, the base station 114a and the WTRUs 102a, 102b, 102c may implement a wireless technology such as IEEE 802.11 (i.e., Wireless Fidelity (Wi-Fi)), IEEE 802.16 (i.e., Worldwide Interoperability for Microwave Access (WiMAX)), CDMA2000, CDMA2000 1X, CDMA2000EV-DO, Interim Standard 2000 (IS-2000), Interim Standard 95 (IS-95), Interim Standard 856 (IS-856), Global System for Mobile Communications (GSM), Enhanced Data Rates for GSM Evolution (EDGE), GSM EDGE (GERAN), or the like.

[0016] 1A may be, for example, a wireless router, a Home Node-B, a Home eNode-B, or an access point and may utilize any suitable RAT to facilitate wireless connectivity in a local area such as a business, a home, a vehicle, a campus, an industrial facility, an air corridor (e.g., for use by drones), a road, etc. In one embodiment, the base station 114b and the WTRUs 102c, 102d may implement a radio technology such as IEEE 802.11 to establish a wireless local area network (WLAN). In an embodiment, the base station 114b and the WTRUs 102c, 102d may implement a radio technology such as IEEE 802.15 to establish a wireless personal area network (WPAN). In yet another embodiment, the base station 114b and the WTRUs 102c, 102d may utilize a cellular-based RAT (e.g., WCDMA, CDMA2000, GSM, LTE, LTE-A, LTE-A Pro, NR, etc.) to establish a picocell or femtocell. 1A, the base station 114b may be directly connected to the Internet 110. Therefore, the base station 114b may not need to access the Internet 110 via the CN 106 / 115.

[0017] The RAN 104 / 113 can communicate with the CN 106 / 115, which can be any type of network configured to provide voice, data, application, and / or Voice over Internet Protocol (VoIP) services to one or more WTRUs 102a, 102b, 102c, 102d. The data can have various quality of service (QoS) requirements, such as different throughput requirements, delay requirements, error tolerance requirements, reliability requirements, data throughput requirements, mobility requirements, etc. The CN 106 / 115 can provide call control, billing services, mobile location-based services, prepaid calling, Internet connectivity, video distribution, etc., and / or perform high-level security functions such as user authentication. Although not shown in FIG. 1A , it will be understood that the RAN 104 / 113 and / or the CN 106 / 115 can communicate directly or indirectly with other RANs that use the same RAT as the RAN 104 / 113 or a different RAT. For example, in addition to being connected to a RAN 104 / 113 that may utilize NR radio technology, the CN 106 / 115 may also communicate with another RAN (not shown) that uses GSM, UMTS, CDMA2000, WiMAX, E-UTRA, or Wi-Fi radio technology.

[0018] The CN 106 / 115 may also serve as a gateway for the WTRUs 102a, 102b, 102c, 102d to access the PSTN 108, the Internet 110, and / or other networks 112. The PSTN 108 may include a circuit-switched telephone network providing plain old telephone service (POTS). The Internet 110 may include a global system of interconnected computer networks and devices that use common communication protocols such as Transmission Control Protocol (TCP), User Datagram Protocol (UDP), and / or Internet Protocol (IP) of the TCP / IP Internet protocol suite. The network 112 may include wired and / or wireless communication networks owned and / or operated by other service providers. For example, the network 112 may include another CN connected to one or more RANs, which may use the same RAT as the RANs 104 / 113 or a different RAT.

[0019] Some or all of the WTRUs 102a, 102b, 102c, 102d in the communications system 100 may include multi-mode capabilities (e.g., the WTRUs 102a, 102b, 102c, 102d may include multiple transceivers for communicating with different wireless networks over different wireless links). For example, the WTRU 102c shown in FIG. 1A may be configured to communicate with a base station 114a that may employ cellular-based wireless technology and with a base station 114b that may employ IEEE 802.2 wireless technology.

[0020] 1B is a system diagram illustrating an example WTRU 102. As shown in FIG. 1B, the WTRU 102 may include, among other things, a processor 118, a transceiver 120, a transmit / receive element 122, a speaker / microphone 124, a keypad 126, a display / touchpad 128, non-removable memory 130, removable memory 132, a power source 134, a global positioning system (GPS) chipset 136, and / or other peripherals 138. It will be understood that the WTRU 102 may include any subcombination of the foregoing elements while remaining consistent with an embodiment.

[0021] The processor 118 may be a general-purpose processor, a special-purpose processor, a conventional processor, a digital signal processor (DSP), multiple microprocessors, one or more microprocessors associated with a DSP core, a controller, a microcontroller, an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA) circuit, other types of integrated circuits (ICs), a state machine, etc. The processor 118 may perform signal coding, data processing, power control, input / output processing, and / or any other functionality that enables the WTRU 102 to operate in a wireless environment. The processor 118 may be coupled to the transceiver 120, which may be coupled to the transmit / receive element 122. While FIG. 1B depicts the processor 118 and the transceiver 120 as separate components, it will be understood that the processor 118 and the transceiver 120 may be integrated together in an electronic package or chip.

[0022] The transmit / receive element 122 can be configured to transmit signals to or receive signals from a base station (e.g., base station 114a) over the air interface 116. For example, in one embodiment, the transmit / receive element 122 may be an antenna configured to transmit and / or receive RF signals. In an embodiment, the transmit / receive element 122 may be an emitter / detector configured to transmit and / or receive IR, UV, or visible light signals, for example. In yet another embodiment, the transmit / receive element 122 may be configured to transmit and / or receive both RF and light signals. It will be understood that the transmit / receive element 122 can be configured to transmit and / or receive any combination of wireless signals.

[0023] 1B as a single element, the WTRU 102 may include any number of transmit / receive elements 122. More specifically, the WTRU 102 may employ MIMO technology. Thus, in one embodiment, the WTRU 102 may include two or more transmit / receive elements 122 (e.g., multiple antennas) for transmitting and receiving wireless signals over the air interface 116.

[0024] The transceiver 120 may be configured to modulate signals transmitted by the transmit / receive element 122 and demodulate signals received by the transmit / receive element 122. As mentioned above, the WTRU 102 may have multi-mode capabilities. Thus, the transceiver 120 may include multiple transceivers to enable the WTRU 102 to communicate via multiple RATs, such as, for example, NR and IEEE 802.11.

[0025] The processor 118 of the WTRU 102 may be coupled to and may receive user input data from a speaker / microphone 124, a keypad 126, and / or a display / touchpad 128 (e.g., a liquid crystal display (LCD) display unit or an organic light emitting diode (OLED) display unit). The processor 118 may also output user data to the speaker / microphone 124, the keypad 126, and / or the display / touchpad 128. Furthermore, the processor 118 may access information from and store data in any type of suitable memory, such as non-removable memory 130 and / or removable memory 132. The non-removable memory 130 may include random access memory (RAM), read-only memory (ROM), a hard disk, or any other type of memory storage device. The removable memory 132 may include a subscriber identity module (SIM) card, a memory stick, a secure digital (SD) memory card, etc. In other embodiments, the processor 118 may access information from and store data in memory that is not physically located on the WTRU 102, such as a server or home computer (not shown).

[0026] The processor 118 may receive power from the power source 134 and may be configured to distribute and / or control the power to other components within the WTRU 102. The power source 134 may be any suitable device for providing power to the WTRU 102. For example, the power source 134 may include one or more dry batteries (e.g., nickel cadmium (NiCd), nickel zinc (NiZn), nickel metal hydride (NiMH), lithium ion (Li-ion), etc.), solar cells, fuel cells, etc.

[0027] The processor 118 may also be coupled to a GPS chipset 136, which may be configured to provide location information (e.g., longitude and latitude) regarding the current location of the WTRU 102. In addition to or instead of information from the GPS chipset 136, the WTRU 102 may receive location information from a base station (e.g., base stations 114a, 114b) over the air interface 116 and / or may determine its location based on the timing of signals received from two or more nearby base stations. It will be appreciated that the WTRU 102 may obtain location information by way of any suitable location-determination method while remaining consistent with an embodiment.

[0028] The processor 118 may further be coupled to other peripherals 138, which may include one or more software and / or hardware modules that provide additional features, functionality, and / or wired or wireless connectivity. For example, the peripherals 138 may include an accelerometer, an e-compass, a satellite transceiver, a digital camera (for photos and / or videos), a universal serial bus (USB) port, a vibration device, a television transceiver, a hands-free headset, a Bluetooth module, a frequency modulation (FM) radio unit, a digital music player, a media player, a video game player module, an internet browser, a virtual reality and / or augmented reality (VR / AR) device, an activity tracker, etc. The peripherals 138 may include one or more sensors, which may be one or more of a gyroscope, an accelerometer, a Hall effect sensor, a magnetometer, a direction sensor, a proximity sensor, a temperature sensor, a time sensor, a geolocation sensor, an altimeter, a light sensor, a touch sensor, a magnetometer, a barometer, a gesture sensor, a biometric sensor, and / or a humidity sensor.

[0029] The WTRU 102 may include a full-duplex radio for transmitting and receiving some or all of the signals (e.g., associated with a particular subframe) on both the UL (e.g., for transmission) and downlink (e.g., for reception) in parallel and / or simultaneously. The full-duplex radio may include an interference management unit 139 for reducing and / or substantially eliminating self-interference either via hardware (e.g., a choke) or a processor (e.g., signal processing via a separate processor (not shown) or processor 118). In an embodiment, the WTRU 102 may include a half-duplex radio for transmitting and receiving some or all of the signals (e.g., associated with a particular subframe on either the UL (e.g., for transmission) or downlink (e.g., for reception) in parallel and / or simultaneously.

[0030] 1C is a system diagram illustrating the RAN 104 and the CN 106 according to an embodiment. As described above, the RAN 104 can communicate with the WTRUs 102a, 102b, 102c over the air interface 116 using E-UTRA radio technology. The RAN 104 can also communicate with the CN 106.

[0031] The RAN 104 may include eNode-Bs 160a, 160b, and 160c, although it will be understood that the RAN 104 may include any number of eNode-Bs while remaining consistent with an embodiment. The eNode-Bs 160a, 160b, and 160c may each include one or more transceivers for communicating with the WTRUs 102a, 102b, and 102c over the air interface 116. In one embodiment, the eNode-Bs 160a, 160b, and 160c may implement MIMO technology. Thus, the eNode-B 160a, for example, may use multiple antennas to transmit wireless signals to and / or receive wireless signals from the WTRU 102a.

[0032] Each of the eNode-Bs 160a, 160b, 160c may be associated with a particular cell (not shown) and may be configured to handle radio resource management decisions, handover decisions, scheduling of users in the UL and / or DL, etc. As shown in FIG. 1C, the eNode-Bs 160a, 160b, 160c may communicate with each other via an X2 interface.

[0033] 1C may include a mobility management entity (MME) 162, a serving gateway (SGW) 164, and a packet data network (PDN) gateway (or PGW) 166. While each of the foregoing elements is shown as part of the CN 106, it will be understood that any of these elements may be owned and / or operated by an entity other than the CN operator.

[0034] The MME 162 may be connected to each of the eNode-Bs 162a, 162b, 162c in the RAN 104 via an S1 interface and may function as a control node. For example, the MME 162 may be responsible for authenticating users of the WTRUs 102a, 102b, 102c, activating / deactivating bearers, selecting a particular serving gateway during initial attachment of the WTRUs 102a, 102b, 102c, etc. The MME 162 may provide a control plane function for switching between the RAN 104 and other RANs (not shown) that use other radio technologies such as GSM and / or WCDMA.

[0035] The SGW 164 may be connected to each of the eNode-Bs 160a, 160b, 160c in the RAN 104 via an S1 interface. The SGW 164 may generally route and forward user data packets to and from the WTRUs 102a, 102b, 102c. The SGW 164 may perform other functions such as anchoring the user plane during inter-eNode-B handovers, triggering paging when DL data is available to the WTRUs 102a, 102b, 102c, managing and storing context for the WTRUs 102a, 102b, 102c, etc.

[0036] The SGW 164 may be connected to a PGW 166, which may provide the WTRUs 102a, 102b, 102c with access to packet-switched networks such as the Internet 110 to facilitate communication between the WTRUs 102a, 102b, 102c and IP-enabled devices.

[0037] The CN 106 may facilitate communications with other networks. For example, the CN 106 may provide the WTRUs 102a, 102b, 102c with access to circuit-switched networks, such as the PSTN 108, to facilitate communications between the WTRUs 102a, 102b, 102c and traditional landline communication devices. For example, the CN 106 may include or communicate with an IP gateway (e.g., an IP Multimedia Subsystem (IMS) server) that serves as an interface between the CN 106 and the PSTN 108. Additionally, the CN 106 may provide the WTRUs 102a, 102b, 102c with access to other networks 112, which may include other wired and / or wireless networks owned and / or operated by other service providers.

[0038] Although the WTRU is depicted in FIGS. 1A-1D as a wireless terminal, it is contemplated that in certain representative embodiments such a terminal may use a wired communication interface (e.g., temporarily or permanently) with the communication network.

[0039] In an exemplary embodiment, the other network 112 may be a WLAN.

[0040] A WLAN in infrastructure basic service set (BSS) mode may have an access point (AP) for the BSS and one or more stations (STAs) associated with the AP. The AP may have access or interface to a distribution system (DS) or another type of wired / wireless network that carries traffic into and / or out of the BSS. Traffic originating from outside the BSS to a STA may arrive through the AP and be delivered to the STA. Traffic originating from a STA to a destination outside the BSS may be sent to the AP and delivered to the respective destination. Traffic between STAs within the BSS may be transmitted through the AP. For example, a source STA may transmit traffic to the AP, and the AP may deliver the traffic to the destination STA. Traffic between STAs within the BSS may be considered and / or referred to as peer-to-peer traffic. Peer-to-peer traffic may be transmitted (e.g., directly) between a source STA and a destination STA using direct link setup (DLS). In certain representative embodiments, the DLS may use 802.11e DLS or 802.11z Tunneled DLS (TDLS). A WLAN using an Independent BSS (IBSS) mode may have no APs, and STAs within or using the IBSS (e.g., all STAs) may communicate directly with each other. The IBSS communication mode may be referred to herein as an "ad hoc" communication mode.

[0041] When using 802.11ac infrastructure mode operation or a similar mode of operation, an AP may transmit beacons on a fixed channel, such as a primary channel. The primary channel may be a fixed width (e.g., a wide 20 MHz bandwidth) or a width dynamically set via signaling. The primary channel may be the operating channel of the BSS and may be used by STAs to establish a connection with the AP. In certain representative embodiments, carrier sense multiple access with collision avoidance (CSMA / CA) may be implemented, for example, in an 802.11 system. With CSMA / CA, STAs (e.g., all STAs), including the AP, may sense the primary channel. If the primary channel is detected / sensed and / or determined to be busy by a particular STA, the particular STA may back off. One STA (e.g., only one station) may transmit on a particular BSS at any time.

[0042] High throughput (HT) STAs may use a 40 MHz wide channel for communication, for example, through a combination of the primary 20 MHz channel with adjacent or non-adjacent 20 MHz channels to form a 40 MHz wide channel.

[0043] A very high throughput (VHT) STA can support channels of 20 MHz, 40 MHz, 80 MHz, and / or 160 MHz width. A 40 MHz and / or 80 MHz channel can be formed by combining contiguous 20 MHz channels. A 160 MHz channel can be formed by combining eight contiguous 20 MHz channels or two non-contiguous 80 MHz channels, which can be referred to as an 80+80 configuration. For the 80+80 configuration, after channel encoding, the data can pass through a segment parser to split the data into two streams. Inverse fast Fourier transform (IFFT) processing and time-domain processing can be performed separately on each stream. The streams can be mapped to two 80 MHz channels, and the data can be transmitted by the transmitting STA. At the receiver of the receiving STA, the above operations for the 80+80 configuration can be reversed, and the combined data can be transmitted to the medium access control (MAC).

[0044] Sub-1 GHz operating modes are supported by 802.11af and 802.11ah. The channel operating bandwidths and carriers are reduced in 802.11af and 802.11ah compared to those used in 802.11n and 802.11ac. 802.11af supports 5 MHz, 10 MHz, and 20 MHz bandwidths in the TV White Space (TVWS) spectrum, while 802.11ah supports 1 MHz, 2 MHz, 4 MHz, 8 MHz, and 16 MHz bandwidths using non-TVWS spectrum. According to representative embodiments, 802.11ah can support metered control / machine-type communications, such as MTC devices, within macro coverage areas. MTC devices may have limited functionality, including support (e.g., support only) of specific bandwidths and / or limited bandwidths. MTC devices may include batteries with above-threshold battery life (e.g., to maintain very long battery life).

[0045] In WLAN systems that can support multiple channels, and channel bandwidths such as 802.11n, 802.11ac, 802.11af, and 802.11ah, the channel bandwidth includes a channel that can be designated as the primary channel. The primary channel may have a bandwidth equal to the largest common operating bandwidth supported by all STAs in the BSS. The bandwidth of the primary channel may be configured and / or limited by the STA from among all STAs operating in the BSS that support the smallest bandwidth operating mode. In the example of 802.11ah, the primary channel of a STA (such as an MTC-type device) that supports (e.g., only supports) 1 MHz mode may be 1 MHz wide, even if the AP and other STAs in the BSS support 2 MHz, 4 MHz, 8 MHz, 16 MHz, and / or other channel bandwidth operating modes. Carrier sensing and / or network allocation vector (NAV) configuration may depend on the status of the primary channel. For example, if the primary channel is busy because a STA (which only supports a 1 MHz mode of operation) is transmitting to the AP, the entire available frequency band may be considered busy, even though most of the frequency band could remain idle and available.

[0046] In the United States, the available frequency band that can be used with 802.11ah is 902MHz to 928MHz. In South Korea, the available frequency band is 917.5MHz to 923.5MHz. In Japan, the available frequency band is 916.5MHz to 927.5MHz. The total available bandwidth for 802.11ah is 6MHz to 26MHz depending on the country code.

[0047] 1D is a system diagram illustrating the RAN 113 and the CN 115 according to an embodiment. As described above, the RAN 113 can communicate with the WTRUs 102a, 102b, 102c over the air interface 116 using NR radio technology. The RAN 113 can also communicate with the CN 115.

[0048] The RAN 113 may include gNBs 180a, 180b, and 180c, although it will be understood that the RAN 113 may include any number of gNBs while remaining consistent with an embodiment. The gNBs 180a, 180b, and 180c may each include one or more transceivers for communicating with the WTRUs 102a, 102b, and 102c over the air interface 116. In one embodiment, the gNBs 180a, 180b, and 180c may implement MIMO technology. For example, the gNBs 180a and 180b may utilize beamforming to transmit signals to and / or receive signals from the gNBs 180a, 180b, and 180c. Thus, the gNB 180a may, for example, transmit wireless signals to and / or receive wireless signals from the WTRU 102a using multiple antennas. In an embodiment, the gNBs 180a, 180b, 180c may implement carrier aggregation technology. For example, the gNB 180a may transmit multiple component carriers to the WTRU 102a (not shown). A subset of these component carriers may be on unlicensed spectrum, and the remaining component carriers may be on licensed spectrum. In an embodiment, the gNBs 180a, 180b, 180c may implement coordinated multipoint (CoMP) technology. For example, the WTRU 102a may receive coordinated transmissions from the gNBs 180a and 180b (and / or 180c).

[0049] The WTRUs 102a, 102b, 102c may communicate with the gNBs 180a, 180b, 180c using transmissions related to scalable numerology. For example, the OFDM symbol spacing and / or OFDM subcarrier spacing may vary for different transmissions, different cells, and / or different portions of the wireless transmission spectrum. The WTRUs 102a, 102b, 102c may communicate with the gNBs 180a, 180b, 180c using subframes or transmission time intervals (TTIs) of varying or scalable lengths (e.g., different lengths of absolute time including and / or lasting different numbers of OFDM symbols).

[0050] The gNBs 180a, 180b, 180c can be configured to communicate with the WTRUs 102a, 102b, 102c in a standalone configuration and / or a non-standalone configuration. In a standalone configuration, the WTRUs 102a, 102b, 102c can communicate with the gNBs 180a, 180b, 180c without accessing another RAN (e.g., eNode-Bs 160a, 160b, 160c, etc.). In a standalone configuration, the WTRUs 102a, 102b, 102c can utilize one or more gNBs 180a, 180b, 180c as mobility anchor points. In a standalone configuration, the WTRUs 102a, 102b, 102c can communicate with the gNBs 180a, 180b, 180c using signals in unlicensed bands. In a non-standalone configuration, the WTRUs 102a, 102b, 102c may communicate / connect with a gNB 180a, 180b, 180c while communicating / connecting with another RAN, such as an eNode-B 160a, 160b, 160c. For example, the WTRUs 102a, 102b, 102c may implement a DC principle to communicate with one or more gNBs 180a, 180b, 180c and one or more eNode-Bs 160a, 160b, 160c substantially simultaneously. In a non-standalone configuration, the eNode-Bs 160a, 160b, 160c may act as a mobility anchor for the WTRUs 102a, 102b, 102c, and the gNBs 180a, 180b, 180c may provide additional coverage and / or throughput for serving the WTRUs 102a, 102b, 102c.

[0051] Each of the gNBs 180a, 180b, 180c may be associated with a particular cell (not shown) and may be configured to handle radio resource management decisions, handover decisions, scheduling of users in the UL and / or DL, support for network slicing, dual connectivity, interworking between NR and E-UTRA, routing of user plane data to User Plane Functions (UPFs) 184a, 184b, routing of control plane information to Access and Mobility Management Functions (AMFs) 182a, 182b, etc. As shown in FIG. 1D , the gNBs 180a, 180b, 180c may communicate with each other via an Xn interface.

[0052] 1D may include at least one AMF 182a, 182b, at least one UPF 184a, 184b, at least one Session Management Function (SMF) 183a, 183b, and possibly a Data Network (DN) 185a, 185b. While each of the foregoing elements is shown as part of the CN 115, it will be understood that any of these elements may be owned and / or operated by an entity other than the CN operator.

[0053] The AMF 182a, 182b may be connected to one or more gNBs 180a, 180b, 180c in the RAN 113 via an N2 interface and may function as a control node. For example, the AMF 182a, 182b may be responsible for authenticating users of the WTRUs 102a, 102b, 102c, supporting network slicing (e.g., handling different PDU sessions with different requirements), selecting a particular SMF 183a, 183b, registration area, termination of NAS signaling, mobility management, etc. Network slicing can be used by the AMF 182a, 182b to customize the CN support of the WTRUs 102a, 102b, 102c based on the type of service being utilized by the WTRUs 102a, 102b, 102c. Different network slices may be established for different use cases, for example, services relying on ultra-reliable low-latency (URLLC) access, services relying on enhanced massive mobile broadband (eMBB) access, services with machine-type communications (MTC) access, etc. The AMF 162 may provide a control plane function for switching between the RAN 113 and other RANs (not shown) that use other radio technologies, such as LTE, LTE-A, LTE-A Pro, and / or non-3GPP access technologies like Wi-Fi.

[0054] The SMFs 183a and 183b can be connected to the AMFs 182a and 182b in the CN 115 via an N11 interface. The SMFs 183a and 183b can also be connected to the UPFs 184a and 184b in the CN 115 via an N4 interface. The SMFs 183a and 183b can select and control the UPFs 184a and 184b and configure the routing of traffic through the UPFs 184a and 184b. The SMFs 183a and 183b can perform other functions such as managing and assigning WTRU IP addresses, managing PDU sessions, controlling policy enforcement and QoS, and providing downlink data notifications. The PDU session type can be IP-based, non-IP-based, Ethernet-based, etc.

[0055] The UPFs 184a, 184b may be connected to one or more gNBs 180a, 180b, 180c in the RAN 113 via an N3 interface, which may provide the WTRUs 102a, 102b, 102c with access to packet-switched networks such as the Internet 110 to facilitate communications between the WTRUs 102a, 102b, 102c and IP-enabled devices. The UPFs 184, 184b may perform other functions such as routing and forwarding packets, enforcing user plane policy, supporting multi-homed PDU sessions, handling user plane QoS, buffering downlink packets, providing a mobility anchor, etc.

[0056] The CN 115 may facilitate communication with other networks. For example, the CN 115 may include or communicate with an IP gateway (e.g., an IP Multimedia Subsystem (IMS) server) that acts as an interface between the CN 115 and the PSTN 108. Additionally, the CN 115 may provide the WTRUs 102a, 102b, 102c with access to other networks 112, which may include other wired and / or wireless networks owned and / or operated by other service providers. In one embodiment, the WTRUs 102a, 102b, 102c may be connected to local data networks (DNs) 185a, 185b via UPFs 184a, 184b via an N3 interface to the UPFs 184a, 184b and an N6 interface between the UPFs 184a, 184b and the DNs 185a, 185b.

[0057] 1A-1D and the corresponding description thereof, one or more, or all, of the functions described herein with respect to one or more of the WTRUs 102a-d, base stations 114a-b, eNode-Bs 160a-c, MME 162, SGW 164, PGW 166, gNBs 180a-c, AMFs 182a-ab, UPFs 184a-b, SMFs 183a-b, DNs 185a-b, and / or any other device(s) described herein may be performed by one or more emulation devices (not shown). The emulation devices may be one or more devices configured to emulate one or more, or all, of the functions described herein. For example, the emulation devices may be used to test other devices and / or to simulate network and / or WTRU functionality.

[0058] The emulation device can be designed to implement one or more tests of other devices in a lab environment and / or an operator network environment. For example, one or more emulation devices can perform one or more or all functions while fully or partially implemented and / or deployed as part of a wired and / or wireless communication network to test other devices in the communication network. One or more emulation devices can perform one or more or all functions while temporarily implemented / deployed as part of a wired and / or wireless communication network. The emulation device can be directly coupled to another device for testing purposes and / or can perform testing using over-the-air wireless communication.

[0059] The one or more emulation devices may perform one or more functions, inclusive, while not implemented / deployed as part of a wired and / or wireless communication network. For example, the emulation devices may be utilized in test scenarios in a test lab and / or in an undeployed (e.g., test) wired and / or wireless communication network to implement testing of one or more components. The one or more emulation devices may be test equipment. Direct RF coupling and / or wireless communication via RF circuitry (e.g., which may include one or more antennas) may be used by the emulation devices to transmit and / or receive data.

[0060] In wireless systems such as those associated with FIGS. 1A-1D described herein, a central node (e.g., a gNB) may serve a set of WTRUs and opportunities to transmit transport blocks (TBs) from the WTRUs to the central node, which may be managed by the central node. For example, the gNB may schedule individual WTRU uplink (UL) transmissions by allocating individual time-frequency resources to each WTRU and granting each resource to one WTRU. Such an arrangement of UL transmissions is sometimes referred to as grant-based UL transmission. Alternatively, the gNB may announce the existence of one or more time-frequency resources and allow a set of WTRUs to use each resource, thereby allowing access without a specific UL grant.

[0061] In some cases, unlicensed bands may be used exclusively or partially in wireless systems where a base station (e.g., a gNB) or a WTRU is required to perform a listen-before-talk (LBT) procedure before accessing an unlicensed wireless channel to ensure fair channel access. Depending on the regulatory requirements for the unlicensed channel, the details of the LBT may vary. Generally, the LBT procedure may consist of a fixed and / or random duration interval in which a wireless node (e.g., a gNB or a WTRU) listens to the medium, and if the energy level detected from the medium exceeds a threshold (specified by a regulatory authority), the gNB or the WTRU refrains from transmitting any wireless signals; otherwise, the wireless node may transmit its desired signal after the duration (i.e., completion of the LBT procedure). The LBT duration interval is the time spent detecting / sensing before transmitting, which means that the longer the LBT duration interval, the longer the time to wait to transmit.

[0062] In general, NR technology can be suitable for many use cases, such as ultra-reliable low-latency communications (URLLC), massive machine-type communications (mMTC or MMTC), or enhanced mobile broadband (eMBB or EMBB) communications. MMTC can enable communication between a large number of low-cost, battery-powered devices, supporting applications such as smart metering, logistics, and field and body sensors. URLLC can enable devices and machines to communicate with ultra-reliability, very low latency, and high availability for applications such as vehicular communications, industrial control, factory automation, remote surgery, smart grids, and public safety applications. EMBB can address the expansion of various parameters, such as data rate, latency, and mobile broadband access coverage. To meet the performance requirements of these use cases, NR can have specific parameters and capabilities.

[0063] NR can specify various numerologies with subcarrier spacing ranging from 15 KHz to 240 KHz. The base subcarrier spacing can be 15 KHz, and other numerologies can have subcarrier spacing increments that are powers of 2, as listed in Table 1. [Table 1]

[0064] The NR Physical Downlink Control Channel (PDCCH) can consist of one or more Control Channel Elements (CCEs), up to 16 CCEs depending on the aggregation level. The Control Resource Set (CORESET) is a set of resources in the frequency domain given by the higher layer parameter CORESET-freq-dom.

number

number

[0065] The NR Physical Uplink Control Channel (PUCCH) can support multiple formats as shown in Table 2. [Table 2]

[0066] In an NR frame, the OFDM symbols within a slot can be classified as "downlink" (denoted "D"), "flexible" (denoted "X"), or "uplink" (denoted "U"). This structure is shown in Table 3. [Table 3]

[0067] In some regulatory regimes, the use of unlicensed channels may require a Listen-Before-Talk (LBT) procedure, resulting in LBT categories in protocols such as Licensed Assisted Access (LAA), enhanced LAA (eLAA), and further eLAA (eLAA). The LBT Category 4 (CAT 4) scheme adopted in LAA / eLAA may be the preferred scheme for some use cases. The LBT CAT 4 procedure is initiated when an eNB or gNB, or possibly a WTRU, wants to transmit control or data on an unlicensed channel. The device can then perform an initial Clear Channel Assessment (CCA), in which the channel is checked to be idle for a certain period of time (i.e., the sum of a fixed period and a pseudorandom period). Channel availability can then be determined by comparing the level of energy (ED) detected across the entire bandwidth of the unlicensed channel with an energy threshold determined by the regulatory authority.

[0068] If the channel is determined to be free, transmission can proceed. Otherwise, the device performs a slotted random backoff procedure, selecting a random number from a specified interval called the contention window. A backoff countdown can be obtained, and transmission can begin when the channel is confirmed to be idle and the backoff counter reaches zero. After the eNB or gNB gains access to the channel, transmission can be permitted for a period called the channel occupation time (COT), but only for a limited period called the maximum channel occupation time (MCOT). CAT4 LBT procedures using random backoff and a variable contention window size can enable fair channel access and good coexistence with other radio access technologies (RATs), such as Wi-Fi and other LAA networks. Examples of LBT categories are: Category 1: no listen interval; Category 2: a listen interval of fixed duration (e.g., 25 μs); Category 3: a listen interval of random duration with a fixed contention window; and Category 4: a listen interval of random duration with an increasing contention window.

[0069] In Category 3 LBT, the transmitter can draw a random number N within a contention window. The size of the contention window can be specified by a minimum and a maximum value of N. The size of the contention window can be fixed. The random number N can be used in the LBT procedure to determine the period for which the channel is sensed as idle before the transmitting entity transmits on the channel.

[0070] In Category 4 LBT, the transmitter may draw a random number N within the contention window. The size of the contention window may be specified by a minimum and maximum value of N. The transmitting entity may change the size of the contention window when drawing the random number N. The random number N may be used in the LBT procedure to determine the duration for which the channel may be sensed as idle before the transmitting entity transmits on the channel.

[0071] As discussed herein, a carrier bandwidth portion (BWP) may be a contiguous set of physical resource blocks selected from a contiguous subset of common resource blocks of a given numerology on a given carrier.

[0072] A WTRU may be configured with up to four carrier BWPs in the downlink, with a single downlink carrier BWP active at a given time. The WTRU may not be expected to receive PDSCH, PDCCH, CSI-RS, or TRS outside of the active BWP. A WTRU may be configured with up to four carrier BWPs in the uplink, with a single uplink carrier BWP active at a given time. If a WTRU is configured with an auxiliary uplink, the WTRU may further be configured with up to four carrier BWPs in the auxiliary uplink, with a single auxiliary uplink carrier BWP active at a given time. The WTRU cannot transmit PUSCH or PUCCH outside of the active BWP.

[0073] For HARQ operation in NR, there can be flexible HARQ feedback timing indicated by a 3-bit PDSCH-to-HARQ timing indicator field. There can be a one-to-one mapping between the corresponding feedback in the PDSCH and PUCCH / UCI. The slot timing between the PDSCH and PUCCH, referred to as K1, can be indicated by a 3-bit field in the DCI, indexing eight RRC-configured values. In DCI format 1-1, these eight values ​​can be mapped to RRC-configured delay values ​​(i.e., the mapping is {000,...,111}->RRC-defined values). In DCI format 1-0, these eight values ​​are mapped to the set of delays {1, 2,...,8}.

[0074] NR can support small processing delays, but not small enough to provide feedback within the same slot (e.g., for a Capability 1 WTRU). For example, for a 30 kHz subcarrier spacing, the L1 processing delay from the end of the PDSCH to the start of the PUCCH can be a minimum of 10 OFDM symbols. N1 can be the number of OFDM symbols from the end of the PDSCH to the start of the PUCCH. The frontloaded DMRS can be 10 and 17 symbols only for SCS=30 kHz and 60 kHz, and the frontloaded + additional DMRS can be 13 and 20 symbols for SCS=30 kHz and 60 kHz. N2 can be the number of OFDM symbols from the end of the PDCCH (i.e., UL grant) to the start of the PUSCH. The frequency-first RE mapping can be 12 and 23 symbols for SCS=30 kHz and 60 kHz.

[0075] NR may support dynamic indication of PUCCH resources and time, and HARQ feedback for multiple PDSCHs may be transmitted using a single HARQ codebook. For dynamically scheduled transmissions, the PUCCH resources and time may be indicated in a scheduling DCI. The association between PDSCH and PUCCH may be based on the PUCCH resources and time indicated in the scheduling DCI, and HARQ feedback for all PDSCHs whose scheduling DCIs indicate the same PUCCH resources and time may be reported together. The latest PDSCH feedback that may be included may be limited by the processing time required for the WTRU to prepare the HARQ feedback.

[0076] NR can aggregate feedback of multiple HARQ processes onto one PUCCH using semi-static or dynamic codebooks.

[0077] For semi-static NR feedback aggregation, the size of the ACK codebook can be determined based on the maximum number of TBs across the cell and the PDCCH monitoring opportunities that can be configured to have ACKs in the same slot. This mode can be more robust to DCI missed detections and false positives than the dynamic mode, but may come at the expense of an increased number of ACK feedback bits. For example, with 8 CBGs and 16 HARQ processes, 128 bits are transmitted per cell to inform HARQ feedback even for a single TB.

[0078] For dynamic NR feedback aggregation, the set of HARQ processes can be dynamically determined for each HARQ process for which feedback needs to be reported. Generally, the size of the HARQ codebook can be determined based on the content of multiple consecutively received DCIs, and based on this, the gNB efficiently conveys codebook attributes to the WTRU. A downlink allocation indicator (DAI, 2 bits) can indicate the number of HARQ processes that need to be reported, and the DAI can be robust against missed / incorrect DCIs. To index the HARQ codebook, the DCI of each scheduling allocation can include a DAI that counts all previous DL allocations, including the current allocation, that may be included in the HARQ codebook. The DAI included in the DCI of the latest DL allocation can determine the size of the HARQ codebook. Even if the WTRU misses some DL allocations, it can still correctly address the HARQ codebook as long as the DAI does not wrap around. The DAI of the DL scheduling DCI may be a step by one compared to the immediately preceding DL scheduling DCI, and if the difference is greater than one, it may indicate that the PDCCH is missing.

[0079] There may be one or more HARQ procedures for grant-less UL transmissions in NR. Grant-less (GF) UL transmissions, also referred to as configured grants, and associated HARQ procedures may have several types and attributes in NR. Type I may be solely via RRC configuration, where the WTRU is configured to access GF resources. Type II may be via RRC configuration and DCI signaling, where the WTRU is configured to access GF resources, and access to GF resources is activated, deactivated, or reactivated by DCI signaling. GF UL transmissions may be configured to be performed on a slot- or minislot-based basis.

[0080] One attribute of the HARQ procedure may be where acknowledgment, HARQ feedback, and retransmissions occur as follows: grant-based retransmission of the TB after a failed GF transmission; and grant-less transmission of the TB with up to K=8 repetitions across consecutive GF resources, terminating early if an implicit acknowledgment indication is received by the WTRU.

[0081] An implicit HARQ attribute may be the absence of explicit HARQ-ACK feedback and may be implicit using an NDI field in the DCI format that explicitly indicates the UL HARQ process ID. An implicit HARQ attribute may also be when the HARQ process ID is equal to floor(X / UL-TWG-periodicity) mod UL-TWG-numbHARQproc, where X = (SFN*SlotPerFrame*SymbolPerSlot+Slot_index_In_SF*SymbolPerSlot+Symbol_Index_In_Slot), and X is the symbol index of the start of the repetition bundle, if the HARQ ID is from a selected resource. An implicit HARQ attribute may also be the HARQ RV sequence determined by RRC configuration (including RV cycling and RV0 repetition).

[0082] HARQ can also be periodic, with multiple TX opportunities repeated in each period. Furthermore, HARQ TX opportunities can be associated with specific RV orders, such as {0,2,3,1}, {0,3,0,3}, and {0,0,0,0}, which can be supported. The initial TX of a recurrence can start with RV0, but the timing can be flexible otherwise.

[0083] In an unlicensed NR (NR-U) environment, when an NR-U device attempts to access an unlicensed channel, it may compete with inter-RAT and intra-RAT devices for channel access. The type and density of inter-RAT devices can depend on the unlicensed channel, and the RAT can be Wi-Fi, LTE LAA, Bluetooth, etc. Intra-RAT devices can be other NR-U devices (e.g., WTRUs or gNBs). For example, for an NR-U WTRU, intra-RAT devices can be other NR-U WTRUs connected to the same gNB, or NR-U gNBs or WTRUs not associated with the same gNB. When attempting to access an unlicensed channel, an NR-U WTRU or gNB may need to compete and coexist fairly with inter-RAT and intra-RAT devices.

[0084] To ensure fair competition and coexistence, in some regulatory domains, if a wireless node wants to access an unlicensed channel, the node may first be required to perform a listen-before-talk (LBT) procedure for a certain period of time, and if no energy above a threshold is detected, the wireless node may be required (i.e., the rules) to be allowed to transmit on the wireless channel for up to a maximum period of time. Thus, for NR-U nodes, a similar LBT procedure can be expected.

[0085] FIG. 2 is an example transmission diagram when a WTRU is unable to successfully complete an LBT. As discussed herein, for any transmission diagram, time 201 may be represented on the horizontal axis by transmissions having several time units (e.g., slots). The slots may be labeled in time relative to slot n. In this example, at 210, the WTRU may receive DL of the PDCCH at slot n-2 and slot n-1, which may indicate UL resources for the PUCCH at slot n+2. At 211, the WTRU may need to refrain from transmitting the HARQ codebook prepared for the TBs transmitted at slots n-2 and n-1 because the WTRU may not be able to successfully complete the LBT for the PUCCH scheduled at slot n+2. Thus, the WTRU in this case may need to refrain from transmitting even if the transmission has timing dependencies that may affect the receiving entity. For example, if the WTRU is to transmit a PUCCH configured with an HARQ codebook and the LBT fails, the WTRU may need to refrain from transmitting it. At 212, the NR gNB may assume that the associated TBs in the previous PDSCH for which the WTRU prepared the HARQ codebook to be transmitted were not correctly received by the WTRU, and the gNB may need to retransmit them in the next transmission (e.g., the next slots n-2 and n-1).

[0086] Figure 2 shows that the NR-U gNB may not receive the HARQ codebook because the WTRU failed the LBT process for the scheduled PUCCH resource. One approach to this problem may be to allow multiple opportunities for PUCCH transmission (e.g., announced in the DCI).

[0087] 3 is an example transmission diagram in which a WTRU may have multiple opportunities for a PUCCH. Time 301 is shown on the horizontal axis by several units of time, such as slots. The slots are labeled with respect to slot n in time. In this example, at 310, the WTRU may receive DL of the PDCCH (i.e., at slot n-2 and slot n-1), which may indicate PUCCH in slot n+2 and slot n+4. At 311, the WTRU may attempt to transmit at the first indicated opportunity in slot n+2, but fails the LBT and must wait until the next opportunity (i.e., slot n+4). At 313, the WTRU retries, successfully completes the LBT in slot n+4, and transmits on the PUCCH.

[0088] In general, multiple resource opportunities can be distributed in time and scheduled across multiple slots, or they can be scheduled in the same one or two consecutive slots but each within a different 20 MHz BWP (i.e., each within a different 20 MHz unlicensed channel). Thus, the PDSCH-to-HARQ-Timing-Indicator field, which is a scalar in NR, can carry multiple values. If the LBT is successful, the WTRU can select the first slot; otherwise, it moves on to the next opportunity, and so on. In the example of FIG. 3, the WTRU fails to successfully complete the LBT for the first scheduled PUCCH in slot n+2, waits for the second scheduled PUCCH in slot n+4, where it successfully completes the LBT, and transmits the prepared HARQ codebook for the TB (i.e., PDSCH) transmitted in slots n-2 and n-1. The set of scheduled PUCCHs can be indicated by the set of PDSCH-to-HARQ timing indicators.

[0089] However, the multiple opportunity approach may have drawbacks. The likelihood of an LBT success at the next opportunity (e.g., slot n+4 in FIG. 3) when the LBT fails at the first opportunity (e.g., slot n+2 in FIG. 3) can be referred to as the channel occupation coherence time (COCT), which may depend on the number of inter-RAT and intra-RAT devices operating in the unlicensed channel and the type of traffic in which each participates. For example, if most of the traffic of active unlicensed devices in the band is video traffic, the COCT may be large, and the likelihood of an LBT success after an LBT failure may be large only if the second LBT observation is longer than the first. If the COCT is large, scheduling multiple PUCCH resources within the same COT may be ineffective, which may have a duration of less than 5 ms or 10 ms, depending on the category for which the COT is established. Allocating multiple PUCCH opportunities to each WTRU may be wasteful because the gNB must allocate multiple PUCCH resources (i.e., the number of resources used for PUCCH may double or triple).

[0090] Furthermore, if the WTRU fails to transmit a PUCCH within a window of opportunity, the gNB may still not have the flexibility to request feedback later, even if the LBT fails on multiple PUCCH resources. NR-U HARQ can initially stick to the NR procedure, in which only one slot for PUCCH transmission is indicated on each PDCCH. However, if the gNB does not receive the expected PUCCH, the gNB can provide a supplemental transmission opportunity, or multiple opportunities, for the PUCCH, so that the WTRU has another opportunity to transmit previously unsent HARQ feedback, possibly along with additional HARQ feedback (i.e., multiple slots for PUCCH transmission can be indicated). Furthermore, even if the WTRU completes the LBT and transmits HARQ feedback, the gNB may not have detected it correctly due to interference or collisions, which may lead to inconsistency between the gNB and the WTRU.

[0091] Efficient resource scheduling for PUCCH transmissions in an NR-U scenario can address these issues. WTRUs can be assigned exclusive resources assigned to each WTRU and non-exclusive resources shared among multiple WTRUs to reduce overhead. The non-exclusive resources can be assigned in a manner that reduces the likelihood of collisions between WTRUs. To implement this, several exclusive PDSCH-to-HARQ timing indicators can be assigned to each WTRU, and one or more non-exclusive PDSCH-to-HARQ timing indicators shared among multiple WTRUs can be assigned. The gNB can prioritize WTRUs that use non-exclusive PDSCH-to-HARQ timing indicators.

[0092] To implement prioritization of several WTRUs for managing non-exclusive resources, the PDSCH-to-HARQ timing indicator may include a priority parameter (e.g., a channel access priority class that determines the priority with which a WTRU accesses the medium to transmit its HARQ feedback). The gNB may explicitly assign a priority parameter to a WTRU for a particular non-exclusive resource. This may be assigned statically (i.e., by RRC configuration), semi-statically (i.e., by a combination of RRC configuration and DCI), or dynamically (i.e., by DCI).

[0093] In another approach, the WTRU may autonomously select its access priority class for a particular non-exclusive resource. For example, the WTRU may select the priority parameter based on the number of non-exclusive resource failures that may have occurred. Alternatively, the WTRU may select the priority parameter based on the number of exclusive and non-exclusive resources that it has been assigned. Thus, a WTRU may have N=N1+N2 HARQ resources, where N1 represents exclusive resources and N2 represents non-exclusive resources. In one example, the access priority class of N2 may be fixed and dependent on the WTRU or traffic type. In another example, the access priority class may change as N2 increases (e.g., N2,1>=N2,1>=N2,3, and N2,x is the xth N2 resource). In another example, the access priority class may depend on the values ​​of N1 and N2, such as where a WTRU with N1=3 and N2=1 may have a lower priority than a WTRU with N1=1 and N3=3.

[0094] 4 is an example of a transmission diagram in which a WTRU may have non-exclusive PUCCH priorities. Time 401 is shown on the horizontal axis and may be divided into time increments (e.g., slots) for some n increments. In any of the diagrams discussed herein, a "space" may refer to a break in the diagram purely for demonstration purposes and is not intended to indicate a missing or non-contiguous time increment, but simply to conserve space in the illustrated example. Furthermore, a space may be the same as or similar to the slot before or after the space, unless otherwise noted.

[0095] In the example of FIG. 4, WTRU1 may receive 410 a PDCCH in slot n-2 with an indication of exclusive PUCCH resources in slot n+2 and an indication of a non-exclusive PUCCH slot in slot n+4 with a priority parameter of 1. WTRU1 may receive and decode the PDSCH in slot n-2, for which it may need to send HARQ feedback. WTRU2 may receive 411 a PDCCH in slot n-1, an indication of exclusive PUCCH resources in slot n+3, and an indication of a non-exclusive PUCCH slot in slot n+4 with a priority parameter of 2. In this example, WTRU2 may have a lower priority than WTRU1. WTRU2 may receive and decode the PDSCH in slot n-1, for which it may need to send HARQ feedback.

[0096] For purposes of this example, it may be assumed that the gNB did not receive a transmission from WTRU1 or WTRU2 in the assigned PUCCH (i.e., slot n+2 or n+3, respectively). For example, in slot n+2, WTRU1 may have performed an LBT to transmit on the PUCCH that failed, so WTRU1 cannot send a transmission on the PUCCH and must wait until slot n+4. Similarly, in slot n+3, WTRU2 may have performed an LBT that failed, so WTRU2 must wait until slot n+4.

[0097] As a result of the failure of both WTRUs' first PUCCH attempts, WTRU1 and WTRU2 may compete for PUCCH resources in slot n+4 at 412, and WTRU2's LBT period is set to a value that is statistically longer than that of WTRU1, thereby making WTRU1 more likely to obtain resources for transmission (i.e., WTRU1 has higher priority) since it will wait less time before transmitting according to the LBT procedure. Because WTRU1 has priority, it may be able to successfully transmit HARQ feedback.

[0098] In some cases, due to collisions / interference at the gNB side, the gNB may not be able to detect the HARQ feedback transmitted from the WTRU. The reason why the gNB is unable to receive the transmission, such as a failed LBT or a missing UCI transmission, may not be distinguishable at the gNB side. If the gNB is unable to detect the feedback at a predefined time position due to the time relationship between the PDSCH and the corresponding feedback, the gNB may subsequently retransmit all corresponding PDSCHs. This can occur in NR operation on licensed channels, but is more likely in NR-U due to highly variable interference and the possibility of collisions at the gNB side due to hidden nodes (e.g., undetectable at the WTRU side). This can cause a mismatch between the gNB and the WTRU in terms of the HARQ codebook of the preceding PDSCH being successfully received by the gNB, potentially resulting in the WTRU flushing its HARQ codebook prematurely.

[0099] 5 is an example transmission diagram in which a WTRU successfully completes the LBT but the gNB is unable to detect a PUCCH. Time may be shown on the horizontal axis 501 in slot increments. At 510, the WTRU may receive an indication at slots n−2 and n−1 for the PUCCH in slot n+2, and may also receive and decode a PDSCH in each slot. At 511, the WTRU may successfully complete the LBT for the PUCCH scheduled in slot n+2 and send HARQ feedback, but the gNB may not be able to detect the transmission due to interference or errors at the receiver. At 512, the gNB may send the next PDCCH to the WTRU in slot n+4 indicating that the PUCCH scheduled in slot n+6 is a supplemental PUCCH, which may include an indication to the WTRU to transmit the HARQ codebook of the previously scheduled PUCCH that was to be received in slot n+2 in addition to the codebook associated with the PDSCH in slot n+4 on the PUCCH in slot n+6. At 513, the WTRU successfully completes the LBT and can transmit the PUCCH in the supplemental allocated resources of slot n+6 with all HARQ codebooks.

[0100] Unlike the example of Figure 5, this problem of the gNB not receiving the expected PUCCH can occur in consecutive attempts, over a single channel occupancy time (COT) or two COTs, etc. For example, the gNB may not receive the expected PUCCH carrying an HARQ codebook on the first set of PDSCH resources, and the gNB may grant the first supplemental PUCCH resource for HARQ codebook transmission; however, until the time of the supplemental resources, the gNB may continue to schedule more PDSCHs (i.e., the second set of PDSCH resources) to the WTRU; thus, there may be additional HARQ feedback or additional HARQ codebooks in addition to the previous HARQ codebook. The WTRU and the gNB need to have the same understanding of the number and type of HARQ codebooks that need to be transmitted by the WTRU, and such common understanding needs to be achieved by at least a predetermined amount of control information that keeps the DCI short. If, even during the first supplementary PUCCH resource, the WTRU is unable to transmit aggregated HARQ feedback (e.g., due to an LBT failure) or the gNB is unable to successfully detect the codebook, then the gNB can give the WTRU another opportunity by allocating a second supplementary PUCCH resource, but until the supplementary resource, the gNB can schedule another set of PDSCH resources (i.e., a third set of PDSCH resources) for the WTRU. It may now be expected that the WTRU aggregates HARQ feedback across all three sets of PDSCH resources and transmits them during the second supplementary PUCCH resource. This situation may continue until there are no more opportunities to schedule aggregated HARQ codebooks during the same COT, which means they may be postponed to the next COT. Also, in a situation where the gNB transmits supplemental transmission opportunities, there may be a mismatch between the expected codebook size transmitted by the gNB and the actual codebook size transmitted by the WTRU.

[0101] To solve this, an additional field in the DCI can indicate to the WTRU that the next PUCCH is a "supplemental transmission," allowing the WTRU to calculate the codebook size as it did for the previous PUCCH transmission. The Extended Downlink Allocation Indicator (EDAI) can be an additional field in the NR-U context described herein. This field of the DCI can carry attributes of the scheduled PUCCH. This field can handle sets or groups of PDSCH resources with consecutive Downlink Allocation Indicators (DAIs) and label them as a group. If the WTRU is expected to form a HARQ codebook for TBs in the current set or group of PDSCH resources, the EDAI field can have a value of 0. If the WTRU is expected to form a HARQ codebook for TBs in the current set or group of PDSCH resources and the immediately preceding set or group of PDSCH resources, the EDAI field can have a value of 1. If the WTRU is expected to form a HARQ codebook for TBs in the current set or group of PDSCH resources and for TBs in the two immediately preceding sets or groups of PDSCH resources, the EDAI field may have a value of 2. If the WTRU is expected to form a HARQ codebook for TBs in the current set or group of PDSCH resources and for TBs in the three immediately preceding sets or groups of PDSCH resources, the EDAI field may have a value of 3. Thus, if the WTRU is expected to form a HARQ codebook for TBs in the current set or group of PDSCH resources and for TBs in Y immediately preceding sets or groups of PDSCH resources, the EDAI field may have a value of Y. As described herein, this general rule may be applicable to other situations where some other time unit or group is used instead of TBs (e.g., transmission, COT, etc.), such that the value of the EDAI field can relate to a current time / group set and a previous time / group set.In this mechanism, a single DCI may request HARQ ACK feedback for all PDSCHs that may be transmitted in one or more PDSCH groups within the same PUCCH.

[0102] If EDAI is non-zero and the WTRU attempts to aggregate two or more previously prepared HARQ codebooks with the current codebook, the WTRU may insert a field between the bitstream of one codebook and the bitstream of the next codebook to enable the gNB to distinguish and analyze the codebooks. This field may be denoted as an HARQ codebook delimiter with a specified bit width (e.g., 2 or 4). When aggregating multiple HARQ codebooks, the WTRU may insert a HARQ codebook delimiter after each HARQ codebook. In one example, if the WTRU receives consecutive PDCCHs with EDAI attributes that do not have consecutive values, the WTRU may infer that it did not detect one or more sets of PDCCHs that led to non-consecutive EDAI values. In such a case, the WTRU may insert one HARQ codebook delimiter for each missing EDAI value. For example, after the WTRU receives a set of PDCCHs with a value of EDAI=0, the WTRU receives a set of PDCCHs with a value of EDAI=2 in the next set of slots or even the next COT. This may indicate that the WTRU has missed one or more PDCCHs with EDAI=1, and therefore the WTRU may not be aware of the number of TBs transmitted during the PDCCHs with EDAI=1. Thus, when the WTRU aggregates the codebook of the first received set of PDCCHs with EDAI=0 and the codebook of the second received set of PDCCHs with EDAI=2, the WTRU may insert additional HARQ codebook delimiters for the missing PDCCH sets with EDAI=1. To further demonstrate this, the WTRU may aggregate the HARQ codebooks as follows: HARQ codebook-EDAI0, HARQ codebook delimiter, HARQ codebook delimiter, HARQ codebook-EDAI2. In this example, PDSCH groups (e.g., PDSCHs in a COT) are dynamically labeled by their respective EDAI indices.In this example, the HARQ codebook for each group indexed by the EDAI associated with the group can be stored within each PDSCH group, or the HARQ codebook for each PDSCH group indexed by the EDAI associated with the group can be stored across all groups.

[0103] 6 is an example transmission diagram in which a WTRU prepares a HARQ codebook according to the DAI (i.e., to calculate a codebook of expected sets of PDSCHs as the gNB expects) and according to the EDAI (i.e., to determine the number of previous sets of HARQ codebooks that need to be included as well). At 610, the WTRU may receive an indication in slot n-2 for a PUCCH in slot n+2 with DAI=1 and EDAI=0. At 611, the WTRU may receive an indication in slot n-1 for a PUCCH in slot n+2 with DAI=2 because the codebook is based on the two PDSCH sets received so far and EDAI=0. At 612, the WTRU performs the scheduled LBT in slot n+2, and in this example, the gNB does not receive the PUCCH because the LBT failed or the LBT was successful but there was interference at the receiver. At 613, the WTRU receives a normal resource allocation (e.g., a PUCCH for n+6, and DAI=3 because this is the third PDSCH), but indicates that EDAI=1 because the gNB did not receive the PUCCH for slot n+2, thereby indicating that the previous set of HARQ codebooks should also be included. At 614, similar to the situation in 612, the gNB does not receive the PUCCH for illustration. As a result, at the next resource allocation at 615, the WTRU may receive an indication of a PUCCH for slot n+9, where DAI=3 and EDAI=2 because the two direct sets of codebooks should now be included. At 616, the gNB may finally receive the PUCCH after a successful LBT by the WTRU in the indicated slot n+9.

[0104] 7 is an example transmission diagram in which a WTRU prepares HARQ codebooks according to the DAI (i.e., to calculate the codebook for the expected PDSCH set) and according to the last value of EDAI (i.e., to determine the number of previous HARQ codebook sets that need to be included as well). The value of EDAI may vary among the set of PDCCH resources. For example, consider two consecutive PDCCH resources (e.g., slots n+2 and n+4) with consecutive DAI values ​​at 712 and 714 indicate the next PUCCH (e.g., slot n+6) for which the WTRU is expected to report the HARQ codebook for the associated PDSCH resource. Furthermore, a PUCCH for the previous set of PDSCH resources at 710 and 711 (e.g., slots n-2 and n-1) can be scheduled between these two PDCCH resources (e.g., slot n+3). At 712, the value of EDAI may be 0 (e.g., in the PDCCH in slot n+2), but when the gNB does not receive the expected codebook for the previous PDSCH set at 713, then in the next PDCCH (e.g., in slot n+4), the gNB may change EDAI to 1 at 714 and increase the size of the PUCCH as well (i.e., may also relocate PUCCH resources to later slots to accommodate the larger PUCCH). Then, at 715, the WTRU may prepare an aggregated codebook that includes the previous HARQ codebook (e.g., the one that the gNB has not received for slots n-2 and n-1) and the new HARQ codebook (e.g., for the two PDSCH resources in slots n+2 and n+4).

[0105] The WTRU can refer to the DAI value to calculate the size of the dynamic codebook. Because the size of DAI is 2 bits, the field may wrap around after four PDCCH / PDSCH transmissions, all of which refer to the next PUCCH. For example, if five consecutive PDCCH / PDSCH transmissions all refer to the next PUCCH, the DAI values ​​in the PDCCH may be "mod(dai,4), mod(dai+1,4), mod(dai+2,4), mod(dai+3,4), mod(dai4), mod(dai+1,4)," respectively, which shows the wraparound effect. However, if fewer than four consecutive PDCCHs are missing, the wraparound may not generate any error (i.e., since both the PDCCH and PDSCH are missing, the WTRU simply reports a NACK for the missing PDCCH resources). Furthermore, if the WTRU misses four or more consecutive PDCCH transmissions, the WTRU may not know the actual number of missed PDCCH resources, which may result in inconsistencies because there is no way to correctly calculate the codebook size. While missing four or more consecutive PDSCHs is unlikely for a licensed carrier, it is more likely to occur in NR-U due to collision / interference at the WTRU side. This can be addressed by making the DAI size larger than 2 bits (e.g., 3 or 4 bits) so that the probability of missing 8 or 16 consecutive PDCCHs is reduced (i.e., corresponding to the possibility of missing more than four PDCCHs) if the DAI is accumulated individually within each group. If the DAI is accumulated across multiple PDSCH groups indexed by the EDAI, the dynamic codebook size can be a multiple of the number of PDCCH / PDSCH transmissions per group (N) (i.e., N × (3 or 4 bits)).

[0106] 8 is an example transmission diagram in which a WTRU aggregates a HARQ codebook based on the EDAI of one or more COTs. Here, the WTRU may aggregate a HARQ codebook from a previous COT (i.e., the immediately preceding COT in this example) if the EDAI field indicates to do so (i.e., EDAI=TBD1). As shown, there may be two COTs 810 and 820. COT 810 may be a slot increment relative to n, and COT 820 may be a slot increment relative to j (e.g., n=j). In general, there may be more than two COTs, but as shown, COT 820 follows COT 820. At 811 (i.e., slot n-2), the WTRU receives an indication of a PUCCH for slot n+2 for DAI=1 and EDAI=0. At 812 (i.e., slot n-1), the WTRU may indicate a PUCCH for slot n+2 with DAI=2 and EDAI=0.

[0107] At 813, the WTRU may be expected to transmit a HARQ ACK on the indicated PUCCH resource at the end of COT 810 (i.e., slot n+2), but the LBT may fail (e.g., a failed LBT or the gNB failed to receive), causing COT 810 to end without the WTRU transmitting. The gNB and WTRU may not know when the next opportunity for PUCCH transmission is. To address this, at 821 (i.e., slot j), the gNB may transmit a PDCCH to the WTRU in the next COT 820 with an indication of EDAI=TBD1 (e.g., in DCI or RRC) indicating that it will transmit a PUCCH to the WTRU in slot j+k with an HARQ codebook that was not transmitted during the last PUCCH opportunity of the previous COT 810, or an aggregated HARQ codebook. The EDAI may indicate a particular PDSCH group or a particular COT, such as a group of PDSCHs for which the PUCCH could not be transmitted in the previous COT. At 822, the WTRU may successfully complete the LBT for the PUCCH (e.g., as indicated by a configured DCI or RRC) and aggregate and send the HARQ ACKs from the previous and current COTs to the gNB. Although this example describes only two COTs, the same techniques can be used for one or more COTs.

[0108] In general, if the WTRU fails the LBT and refrains from transmitting a PUCCH, the WTRU retains the HARQ codebook until the next COT, and if the WTRU receives a PDCCH with EDAI=TBD1, the WTRU can do one of the following: 1) if the DCI indicates only the next PUCCH without any PDSCH, the WTRU may transmit the codebook on the indicated next PUCCH resource; or 2) if the DCI indicates the next PUCCH along with a PDSCH resource, the WTRU may aggregate the previous codebook with the new HARQ codebook and transmit the aggregated result on the indicated next PUCCH resource. Even if the WTRU successfully completes the LBT procedure and transmits a PUCCH, the WTRU may retain the HARQ codebook until the next COT and / or until the WTRU receives a PDCCH with a value less than EDAI=TBD1 (e.g., EDAI=0), after which the WTRU may discard the previous HARQ codebook.

[0109] The TBD1 value may, for example, be 3 if EDAI has a bit width of 2, or 7 if EDAI has a bit width of 3. Alternatively, TBD1 may be 1, and such a value for the first unicast PDCCH to the WTRU of the new COT has the same interpretation as above. As discussed herein, the EDAI value shown and used with respect to the example of FIG. 8 represents a value that serves as an indication to the WTRU to aggregate all pending HARQ codebooks for several groups / times (e.g., TB, COT, etc.) until the next uplink opportunity, and the value may be one or more numbers, letters, and / or symbols that can convey this meaning.

[0110] In one scenario, the gNB transmits a TB to the WTRU, and there may be two consecutive COTs during which the WTRU failed the LBT or the gNB was unable to correctly detect the PUCCH during the scheduled PUCCH opportunity, which may result in two sets of pending HARQ codebooks at the WTRU side. Furthermore, if the field EDAI has a value of TBD2 in the received DCI, it may indicate that the WTRU should aggregate the HARQ codebook of the current COT with the pending HARQ codebooks (e.g., each prepared during the two immediately preceding COTs) in the scheduled PUCCH resource indicated in the same DCI with EDAI=TBD2, if necessary. In other scenarios, for any EDAI value of TBD#, # may indicate a numeric value associated with the number of COTs (e.g., counting the current and / or previous COTs to arrive at the numeric value). The EDAI value of TBD# may indicate a numeric value associated with a particular COT.

[0111] In some circumstances, when the WTRU transmits an HARQ codebook in a scheduled PUCCH, the WTRU may not discard the HARQ codebook unless the next scheduled PUCCH has attribute EDAI = 0. This may help the WTRU to verify that the gNB correctly decoded the previously transmitted PUCCH and that there is no need to retransmit the HARQ codebook.

[0112] 9 is an example transmission diagram in which a PUCCH resource allocation is outside the current COT and a PUCCH from a later COT is used. In this example, there may be two COTs 910 and 920. At 901, the gNB may schedule a PUCCH in theoretical slot n+3, which may be outside the current COT 910. The WTRU may infer that the scheduled PUCCH is outside the current COT 910 if the PDSCH-to-HARQ timing indicator field in the PDCCH indicates a timing instance outside the determined end time of the current COT. At 902, if the WTRU determines that the scheduled PUCCH falls after the end of the current COT, the WTRU may not continue with the PUCCH transmission and may keep the HARQ codebook pending for the next transmission. This is when the WTRU receives a new PDCCH with an EDAI (e.g., indicated in DCI or RRC) that has the attributes of the scheduled PUCCH for slot j+2 of COT 920. At 904, the WTRU may transmit the pending HARQ codebook along with the new codebook (i.e., the aggregated HARQ ACK) in the newly scheduled PUCCH. In the first PDCCH / DCI of the new COT, the gNB may set EDAI=TBD1, similar to the example in FIG. 8, to indicate to the WTRU that the pending HARQ codebook is expected to be transmitted along with the newly formed HARQ codebook. Note that the arrows indicate that the HARQ ACK for each PDSCH is transmitted in slot j+2. Although not shown, if the WTRU does not receive a new PDCCH in a subsequent COT for a corresponding PDSCH reception in the current COT, the WTRU may transmit the associated HARQ codebook in the PUCCH resource provided by higher layers.

[0113] In some cases, if the WTRU detects a PDCCH in the current COT but the DCI does not include a PDSCH-to-HARQ timing indicator field, the WTRU may assume that the gNB has not assigned a PUCCH resource to the WTRU for corresponding PDSCH reception in the current COT. Thus, the WTRU may transmit a pending HARQ codebook on the PUCCH resource in a subsequent COT, similar to the examples of Figures 8 and 9. In this case, assuming the WTRU receives a PDSCH in slot n in the current COT, the WTRU may determine a PUCCH resource in slot n+k in the subsequent COT, where k is the number of slots provided by higher layers or the PDSCH-to-HARQ timing indicator field of the DCI received in the subsequent COT.

[0114] In some cases, if the WTRU detects that the scheduled PUCCH falls after the end of the current COT, the WTRU can transmit the PUCCH after the COT ends after performing the appropriate LBT process. Even if the COT period has expired, the WTRU can still transmit the PUCCH in the same way as a device in an unlicensed channel (e.g., not monitored by the COT), but the WTRU must perform an LBT process whose category depends on the period after the end of the COT the scheduled PUCCH is. If the scheduled PUCCH is within 16 μs of the end of the COT, the WTRU can transmit the PUCCH using Cat-1 LBT, which can be considered the same as no LBT. If the scheduled PUCCH is within 25 μs of the end of the COT, the WTRU can transmit the PUCCH using Cat-2 LBT, which can be referred to as one-shot LBT. If the scheduled PUCCH is 25 μs after the end of the COT, the WTRU may transmit the PUCCH using Cat-3 LBT, and the WTRU may calculate the listen interval using the highest priority class. If the scheduled PUCCH is 25 μs after the end of the COT and the WTRU plans to transmit a TB within the configured granted resources after the PUCCH transmission, the WTRU may transmit the PUCCH using Cat-4 LBT. In the above case, the gNB may request the WTRU to retransmit the HARQ codebook (i.e., by setting EDAI=TBD1), so that the WTRU can retain the HARQ codebook until the next COT established by the gNB.

[0115] As discussed herein, due to the successful operation of the NR-U LBT procedure, LBT can be an effective approach for inter-RAT and intra-RAT coexistence. However, the LBT listen interval can waste bandwidth resources, and frequent invocation of the LBT procedure can reduce channel access efficiency. Therefore, it may be beneficial to have a single DL-to-UL switch time in the COT so that the LBT procedure can be invoked once. The gNB can schedule the WTRU's DL / UL in the COT with a single switch point with no or a very small gap. If there is an LBT rule for a gap of less than 16 μs and it can be captured in LBT Category 1, the rule can be useful for this, in which case the responding device (e.g., the WTRU) does not need to perform a listen interval when the gap is less than 16 μs. For example, some 802.11 technologies can take advantage of this, and the responding station can send an acknowledgment to a frame with a duration of 16 μs. Therefore, the NR-U frame structure can be adapted to these efficient coexistence situations without LBT in the COT, where a gNB may address multiple WTRUs in the COT.

[0116] For reference, the switching gap (from DL to UL) can be scheduled and indicated in the SFI as follows: "DL(WTRU1), DL(WTRU2), LBT, UL(WTRU1), DL(WTRU3), LBT, UL(WTRU2), DL(WTRU1), ...." Here, the switching gap can be one OFDM symbol, and the duration of the gap can be longer than 16 μs depending on the numerology. In such cases, the WTRU may need to perform processing other than Cat-1 LBT (e.g., if the duration is less than 25 μs, the WTRU can perform Cat-2 LBT). However, performing LBT can mean that the WTRU needs to be in receive mode, but only a limited portion of the baseband unit is used, and some switching time may be required for the WTRU to switch to transmit mode before it successfully completes the LBT.

[0117] In one scenario, the gNB can schedule multiple WTRUs in a manner that does not require a DL / UL switching gap. This can be a scheduling issue for the gNB, such that a DL symbol is addressed to a first WTRU and the next UL symbol is addressed to a second WTRU. For example, the scheduling can be DL(WTRU1), DL(WTRU2), UL(WTRU1), DL(WTRU3), UL(WTRU2), DL(WTRU1), ... In this example, WTRU1 is notified about its next UL transmission and is also notified to prepare for a gapless UL transmission.

[0118] Generally, in these examples related to switching UL / DL, slot boundaries may be intentionally ignored, but it may be understood that the UL symbols may be located in the last few symbols of the slot. Also, the DL and UL portions may be of different sizes. Furthermore, the notation DL(WTRU1) may refer to one or more DL symbols, such as at the beginning of the slot of the first WTRU (i.e., WTRU1) that may transmit PDCCH and / or PDSCH resources.

[0119] 10 is an example transmission diagram in which a WTRU checks the attributes of a scheduled PUCCH resource and, if no-LBT-PUCCH has a value of true, the WTRU does not perform a listen interval (i.e., there is no gap) immediately before the PUCCH. At 1011, the WTRU may check the attributes of the scheduled PUCCH resource in the DCI in the PDCCH with a matching RNTI, where the gNB may indicate a PUCCH in slot n+3, DAI=0, and no-LBT-PUCCH=true to the WTRU. At 1012, the gNB may indicate a PUCCH in slot n+3, DAI=1, and no-LBT-PUCCH=true to the WTRU. If no-LBT-PUCCH has a true value, the WTRU may use the associated time and frequency attributes to infer that for the next PUCCH (i.e., slot n+3), there may not be a gap immediately before the PUCCH UL transmission, and therefore the WTRU may not need to perform a listen interval immediately before the PUCCH, as shown in 1013. The gNB may schedule DL symbols before the PUCCH resources so that the DL channel is not addressed to the WTRU.

[0120] Also, at 1013, if the WTRU detects a scheduled PUCCH resource in the DCI in the PDCCH with a matching RNTI and the no-LBT-PUCCH subfield has a true value, the WTRU may temporarily override the value of the latest SFI (e.g., for only the slot in which the PUCCH is located) and select one or more OFDM symbols before the scheduled PUCCH as the “X” symbol during which the WTRU transitions from downlink reception to UL transmission. The WTRU may overwrite the latest SFI value when determining the “X” symbol such that the gNB can engage in dynamic operation to schedule PUCCH resources for WTRUs that utilize Cat-1 LBT (e.g., or no LBT for a 16 μs period).

[0121] In another scenario, the gNB may provide a gap interval sufficient for the WTRU to perform a 25 μs LBT procedure (e.g., one-shot LBT) and switch from DL symbols to UL symbols. The scheduling may be “DL(WTRU1), DL(WTRU1), DL(WTRU1), DL(WTRU1), DL(WTRU1), LBT, UL(WTRU1), …,” where the LBT period exceeds one or two OFDM symbols depending on the numerology. The WTRU may inspect the attributes of the scheduled PUCCH resource in the DCI in the PDCCH with a matching RNTI. If the one-shot LBT-PUCCH has a TBD3 value, the WTRU may infer that there may be a gap of one or more symbols immediately before the PUCCH UL transmission for the next PUCCH (i.e., associated time and frequency attributes). Therefore, the WTRU may need to perform a 25 μs listen interval immediately before the PUCCH and immediately after it to prepare to switch if the LBT is successful. If the WTRU detects a scheduled PUCCH resource in the DCI of the PDCCH where the no-LBT-PUCCH subfield matches the RNTI with value TBD3, the WTRU may temporarily override the value of the latest SFI (e.g., for only the slot in which the PUCCH is located) and select one or more OFDM symbols before the scheduled PUCCH as "X" symbols (e.g., see Table 3 for D / X / U symbols), during which the WTRU may transition from downlink reception to UL transmission. However, the transition may be conditional on a successful one-shot LBT in the 25 μs interval immediately preceding the transition.

[0122] For transmissions in NR with configured grant (CG) or without grant, the WTRU may be configured to transmit TB with up to K=(1, 2, 4, 8) repetitions in a set of (i.e., RRC-configured) grant-free resources. Similar or identical grant-free procedures may exist in NR-U, and some WTRU behavior regarding channel access and related LBT procedures may need to be adapted. If the gNB has established a COT with some grant-free resources, the WTRU may initiate grant-free transmissions within the COT established by the gNB. For grant-free resources within the COT, the WTRU may perform an LBT procedure to access the resources.

[0123] In one example, the WTRU may perform an LBT procedure (e.g., LBT Cat-2, 3, or 4) once, e.g., immediately before the first grant-less resource that the WTRU attempts to access, and then, if the LBT procedure is successful, the WTRU may access the remaining grant-less resources in the COT using either no LBT (i.e., LBT Cat-1), or one-shot LBT (LBT Cat-2), or LBT Cat-3. Depending on the value of K, the WTRU may reach the end of the COT without completing K repetitions of the TB (i.e., as specified in the K-repetition grant-less UL transmission).

[0124] In one example, the WTRU may perform a more robust LBT Cat-4 before accessing the first unauthorized resource outside the COT, and for accessing subsequent unauthorized resources outside the COT, the WTRU may perform no-LBT or Cat-1.

[0125] In one example, the WTRU may perform LBT Cat-3 before accessing the first unauthorised resource outside the COT, and to access subsequent unauthorised resources outside the COT, the WTRU may perform no-LBT or one-shot LBT.

[0126] In one example, the WTRU may be configured, or may be indicated by the gNB, to perform a one-shot LBT procedure (Cat-1) before accessing the first and each subsequent grant-less resource outside the COT.

[0127] In one example, the WTRU may refrain from transmitting on resources outside the COT.

[0128] As discussed herein, there may be situations in NR-U transmissions where the WTRU needs to transmit outside the original COT and multiple COTs may be required. If there are multiple COTs, the WTRU may need to send an acknowledgment in another COT and adjust the contention window.

[0129] The transmission of the acknowledgment may be delayed to another COT, for example, because data transmission may occur in COT1 and the transmission of the acknowledgment may occur in COT2. In this case, the transmission of the acknowledgment may follow the success of the LBT. In one example, the reception of the HARQ codebook may also require an acknowledgment, such as when the WTRU performs the LBT and transmits a UL acknowledgment in an UL time slot. The gNB may need to confirm the receipt of the acknowledgment in the next DL time slot. In this way, the WTRU can know whether the transmission was successful and can therefore adjust its contention window for the next LBT accordingly.

[0130] In an example with an ACK in a separate COT, the UL acknowledgement transmission from the WTRU may be poll-based. To improve efficiency, a group polling mechanism may be used.

[0131] In an example with an ACK in a separate COT, the gNB may perform an LBT to acquire the channel, and then the gNB may transmit a group-common DCI to one or more WTRUs for acknowledgment polling. A set of frequency / time resources may be allocated for acknowledgment transmissions from multiple WTRUs. The WTRU may receive the group-common DCI, have an UL acknowledgment to send, and transmit the acknowledgment using the assigned frequency / time resources. The WTRU may perform an LBT at a fixed period before the UL transmission, or the WTRU may simply transmit on the assigned resources without needing to perform an LBT. In one example, the WTRU may randomly select one or more resources to transmit on.

[0132] In an example with ACKs in separate COTs, the gNB may perform an LBT to acquire a channel, and then the gNB may transmit a group of DCIs to a group of WTRUs to perform an acknowledgment poll. A set of frequency / time resources may be allocated for acknowledgment transmissions from multiple WTRUs. The WTRU may receive the group-common DCI, have an UL acknowledgment to transmit, and may transmit the acknowledgment using the allocated frequency / time resources. In one example, the WTRU may randomly select one or more resources to transmit.

[0133] FIG. 11 is an exemplary procedure for adjusting the contention window according to the cumulative number of acknowledgments sent.

[0134] In general, the transmission of acknowledgments in NR-U may require the performance of LBT. A device may be unable to transmit due to an LBT failure, or a device may transmit an acknowledgment but the transmission may fail due to a collision. In such cases, the device may wait for the medium / channel to become available again and then perform LBT. If the transmission fails, the device may need to increase the contention window size so that it can derive a larger random backoff value. However, delayed acknowledgment transmissions may result in delayed data transmissions and create a congested channel. To address this, a device may reduce the size of the contention window or shorten the remaining backoff period if acknowledgments are accumulated. In this case, the device may have a separate random backoff procedure for acknowledgment transmissions.

[0135] As shown in FIG. 11, at 1102, the WTRU may determine a contention window size CWp, where CW min ≦CW p ≦CW max and CW min and C.W. max may be predefined / predetermined or signaled. At 1104, the WTRU selects a random backoff number R∈[0, CW p ] may be derived. At 1106, the WTRU may detect that the signal energy level is below a predefined threshold for a certain period of time, and the WTRU may have an ACK / NACK pending. At 1108, the WTRU may check whether R>0.

[0136] If R is greater than zero, the WTRU may continue to monitor the channel / medium for T timeslots at 1110. If the channel is free during the timeslot, the WTRU may set R=R−1 at 1114. Otherwise, the WTRU may set the number of cumulative acknowledgments to be sent, Nack and the WTRU can check R=f(R,N ack ) can be set. The function f can be predefined or predetermined. In one example,

number

[0137] If R is not greater than zero (i.e., if R reaches 0), the WTRU may transmit an ACK / NACK to the gNB at 1116. At 1118, the WTRU may recognize / determine whether the transmitted ACK / NACK was successful. If it was successful, at 1020, the WTRU may p =CW min and a new random backoff number may be derived for the next ACK / NAK transmission at 1104. If the ACK / NACK transmission is not successful, the WTRU may adjust the remaining random backoff value R at 1112. The WTRU may adjust the remaining random backoff value R by R=f(R, N ack ) can be set.

[0138] In the example procedure of FIG. 11, the WTRU uses N ack At the WTRU side, N ack The manner in which N is maintained may be implementation-related. For example, when the WTRU receives a valid DCI corresponding to a PDSCH transmission to the WTRU, the WTRU may increment N by one. ack When the WTRU notices that the previous acknowledgment transmission was successful, the WTRU may increase the number of ack For example, the WTRU may reset

number

number

[0139] As discussed herein, in NR-U transmissions, a WTRU or gNB may continue transmitting in an unlicensed channel for a maximum period after a successful LBT procedure is performed. In some cases, it may be necessary to share the COT. When a device, such as a WTRU or gNB, initiates a COT in an unlicensed channel, the second device may also share the COT with another device, such as a gNB or WTRU, respectively, transmitting during the COT. For example, if a gNB initiates and "owns" the COT (i.e., gNB-owned COT), it may share it with one or more WTRUs, or if a WTRU initiates and "owns" the COT (i.e., WTRU-owned COT), it may share it with its gNB. COT sharing may be restricted to some rules for better coexistence as well as more efficient transmission and reception in unlicensed channels. Using COT sharing in NR-U may enable better coexistence and more efficient transmission and reception in unlicensed channels.

[0140] For configured grant (CG) or grantless transmission, the WTRU may perform an LBT procedure (e.g., LBT CAT-3 or CAT-4) and establish a COT for which the LBT procedure is associated with a priority class. The WTRU may transmit a pending TB to the gNB using the CG transmission rules. The WTRU may then share its COT, i.e., the WTRU-owned COT, with the gNB. The gNB may use the shared COT for several purposes. For example, the gNB may send a CG-DFI to a WTRU carrying HARQ feedback for a previous TB transmission or a TB transmission before establishing the COT. The gNB may also transmit the TB to the same WTRU or other WTRUs.

[0141] For more efficient COT sharing, the WTRU can indicate COT attributes to the gNB. These attributes can be transmitted by the WTRU to the gNB in ​​the last or last few CG PUCCH transmissions, possibly transmitted in the CG-UCI. The COT attributes transmitted in the CG-UCI can include the following: the duration of the COT (e.g., total duration, a breakdown of the duration, such as the duration expected to be used by the WTRU that owns the COT, and / or the remaining portion of the COT); the access category (AC) or access priority class for which the COT is established; whether the gNB is permitted to use the COT for DL ​​transmissions to other WTRUs; and / or whether the gNB is permitted to use the COT to schedule UL transmissions of other WTRUs.

[0142] When a gNB starts transmitting in a WTRU-shared COT, the gNB may announce the COT attributes to other WTRUs. The (WTRU-shared) COT attributes may be part of the COT attributes that the gNB transmits at the start of the COT and / or retransmits at the start of subsequent slots of the COT. The gNB may transmit this at the start of the COT or at the start of a shared transmission.

[0143] COT sharing can be performed between two or more WTRUs (e.g., when two WTRUs are engaged in CG transmission to their gNB). For example, WTRU1 can start a COT and transmit its pending TB in a CG PUSCH. WTRU2 can then transmit its own CG PUSCH using the same COT. However, WTRU2 may need to inform WTRU1 about its owned COT. In one approach, WTRU1 can send its COT attributes to the gNB indicating that other WTRUs can use the remaining COT. The gNB then announces such COT attributes to other WTRUs in a group common (GC) PDCCH.

[0144] The COT established by the WTRU can be for CG or autonomous uplink (AUL) transmission. If this COT is shared with the gNB, the shared COT can be used between the CG (or AUL) and scheduled or grant-based UL transmissions. For example, the gNB can use the shared COT owned by WTRU1 to schedule WTRU2's grant-based (or scheduled UL). However, for this to occur, the gNB may need to be aware of the fact that WTRU2 has a pending TB for transmission. In some cases, the gNB may have received the WTRU's scheduling request (SR) in the previous or immediately previous COT and / or may not have had time or scheduled resources to schedule the WTRU's UL transmission in that COT. Alternatively, after the gNB starts using the shared COT, the gNB may schedule SR resources for all WTRUs in the first or first few slots, which can be used to indicate to the gNB that they have pending TBs. After receiving the SR from the WTRU, the gNB may schedule the UL in the remaining portion of the shared COT owned by shared WTRU1.

[0145] If the WTRU intends to share its owned COT with the gNB, the WTRU may perform one or more actions to enable the gNB to start downlink transmission within a gap limited by regulatory rules (e.g., if the gap may be 25 μs in duration). If the gNB starts transmitting within this gap, COT sharing can be performed within regulatory rules. Otherwise, if the gNB cannot start transmitting within the duration of the gap, the gNB may need to perform a full LBT procedure (CAT3 or CAT4) before being able to transmit. To increase the likelihood that the gNB will successfully use the WTRU-owned shared COT, the WTRU may perform one or more of these actions.

[0146] One such action may be when the WTRU extends the cyclic prefix (CP) of one or several last symbols to align the end of its transmission within a regulated period, such as 25 μs, before the start of the next slot or the start of the next opportunity the gNB can start a minislot. Note that the CP extension may be indicated in advance by the WTRU to the gNB, like CG-UCI.

[0147] One such action may be when the WTRU transmits a sounding reference signal (SRS) in the last one or several symbols of the slot within a restricted period, such as 25 μs, before the start of the next slot or the start of the next opportunity that the gNB can start a minislot.

[0148] The COT attribute may also report some measurements from the WTRU that obtained the COT (e.g., RSSI, Reference Signal Received Power (RSRP), etc.). COT sharing may be prioritized between a set of WTRUs and gNBs, among which one device acts as a primary (or master) node and the others act as secondary (or slave) nodes.

[0149] FIG. 12 is an example transmission diagram of basic COT sharing. Generally, basic COT sharing can be used in scenarios where the WTRU has a low traffic load or in sparse situations where the hidden node problem is less pronounced. In FIGS. 12 and 12A, each box may represent one or more slots. A COT period 1220 may include a WTRU1 COT 1222 and a COT sharing portion 1224. Initially, at 1201, the WTRU may acquire a COT by performing an LBT (e.g., to transmit in a pre-configured CG / grant-less resource). In the first transmission after acquisition, the WTRU may transmit COT attributes to the gNB and other attributes related to the WTRU CG transmission at 1202. These attributes may be carried on the UCI multiplexed in the PUSCH. Once the PUSCH transmission is complete, the gNB may take over (i.e., share) the COT at 1203, in which case one or more of the following may occur: the gNB announces the COT attributes in the GC-PDCCH, also at 1203; the gNB transmits a PDCCH using the WTRU allocation at 1204; the gNB / WTRU transmits a PDSCH / PUSCH based on the PDCCH allocation at 1205; and / or the gNB / WTRU transmits a PUCCH / PDSCH based on the received PDSCH / PUSCH (i.e., in the case of an ACK) at 1206.

[0150] Alternatively, the COT sharing procedure may include additional procedures to limit the impact of hidden nodes. Figure 13 is an example transmission diagram of COT sharing that limits the effect of hidden nodes. A COT period 1320 may include a WTRU1 COT 1322 and a COT sharing portion 1324. Initially, the WTRU may acquire a COT based on the LBT (e.g., for transmitting in pre-configured CG / grant-free resources) at 1301. At the first transmission after acquisition, the WTRU may transmit COT attributes to the gNB at 1302. These COT attributes may be carried by a short transport block that enables UCI multiplexed in the PUSCH, a short PUCCH, or a modified SR using UCI in the PUCCH. Upon receiving the WTRU COT attributes at the gNB, the gNB may transmit shared COT attributes at 1303, which may be the exact COT attributes requested by the WTRU or a modified set of COT attributes requested by the WTRU that includes the WTRU's reserved attributes and additional shared COT attributes. The WTRU may then transmit its desired data on a PUSCH to the gNB at 1304. Upon completion of the PUSCH transmission, the gNB may take over the COT, where the gNB may transmit a PDCCH per the WTRU assignment 1305, the gNB / WTRU may transmit a PDSCH / PUSCH based on the PDCCH assignment 1306, and / or the gNB / WTRU transmits a PUCCH / PDSCH (in the case of an ACK) based on the received PDSCH / PUSCH 1207.

[0151] Although features and elements are described above in particular combinations, those skilled in the art will understand that each feature or element can be used alone or in any combination with the other features and elements. Furthermore, the methods described herein can be implemented in a computer program, software, or firmware embodied in a computer-readable medium for execution by a computer or processor. Examples of computer-readable media include electronic signals (transmitted via wired or wireless connections) and computer-readable storage media. Examples of computer-readable storage media include, but are not limited to, read-only memory (ROM), random-access memory (RAM), registers, cache memory, semiconductor memory devices, magnetic media such as internal hard disks and removable disks, magneto-optical media, optical media such as CD-ROM disks, digital versatile disks (DVDs), etc. A processor in association with software can be used to implement a radio frequency transceiver for use in a WTRU, UE, terminal, base station, RNC, or any host computer.

Claims

1. 1. A method performed by a wireless transmit receive unit (WTRU), comprising: receiving one or more physical downlink shared channels (PDSCHs) during a first channel occupation time (COT); receiving a physical downlink control channel (PDCCH) at a second COT with control information; receiving one or more PDSCHs at the second COT; aggregating HARQ feedback of the one or more PDSCHs of the first COT and the one or more PDSCHs of the second COT based on the control information; transmitting the aggregated HARQ feedback on a physical uplink control channel (PUCCH) of the second COT based on resources indicated in the control information; A method comprising:

2. 2. The method of claim 1, further comprising: performing listen-before-talk (LBT) before transmitting the aggregated HARQ feedback on the PUCCH of the second COT.

3. 3. The method of claim 2, further comprising: decoding the one or more PDSCHs of the first COT and the one or more PDSCHs of the second COT; and determining HARQ feedback for each PDSCH of each COT.

4. The method of claim 3 , wherein the control information includes an Extended Downlink Allocation Indicator (EDAI) indicating a group or time for aggregating HARQ feedback.

5. The method of claim 4 , further comprising determining to aggregate the first PDSCH and the second PDSCH based on the EDAI.

6. The method of claim 1 , wherein the indicated resources are exclusive or non-exclusive.

7. The method of claim 1 , wherein the indicated resource includes a priority parameter.

8. 1. A wireless transmit receive unit (WTRU), comprising: a transceiver coupled to a processor, the transceiver and the processor configured to receive one or more physical downlink shared channels (PDSCHs) during a first channel occupancy time (COT); the transceiver and processor are further configured to receive one or more PDSCHs at a second COT and a physical downlink control channel (PDCCH) with control information at the second COT; The WTRU is configured such that the transceiver and processor aggregate HARQ feedback for the one or more PDSCHs of the first COT and the one or more PDSCHs of the second COT based on the control information, and transmit the aggregated HARQ feedback on a physical uplink control channel (PUCCH) of the second COT based on resources indicated in the control information.

9. 10. The WTRU of claim 8, wherein the transceiver and processor are further configured to perform listen-before-talk (LBT) before transmitting the aggregated HARQ feedback on the PUCCH of the second COT.

10. 10. The WTRU of claim 9, wherein the transceiver and processor are further configured to decode the one or more PDSCHs of the first COT and the one or more PDSCHs of the second COT and determine HARQ feedback required for each PDSCH of each COT.

11. The WTRU of claim 10 , wherein the control information includes an extended downlink allocation indicator (EDAI) that indicates a group or time for aggregating HARQ feedback.

12. The WTRU of claim 11 , wherein the transceiver and processor are further configured to determine to aggregate the first PDSCH and the second PDSCH based on the EDAI.

13. The WTRU of claim 8 , wherein the indicated resources are exclusive or non-exclusive.

14. The WTRU of claim 8 , wherein the indicated resource includes a priority parameter.

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